Long Term Evolution (LTE) Licensed Assisted Access (LAA) and its enhancements/further enhancements (eLAA/FeLAA) were introduced in 3GPP Releases 13-15 to specify downlink (DL) and uplink (UL) LTE operation in unlicensed spectrum, primarily 5 GHz. A similar effort is under way in Rel-16 for 5G New Radio in unlicensed spectrum (NR-U).
User equipment (UE) can be configured with up to four bandwidth parts (BWPs) in the uplink with a single uplink BWP being active at a given time. UL BWP switching is indicated via Downlink Control Information (DCI) carrying UL scheduling grants sent by the next generation Node-B (gNB). If a UE is configured with a supplementary uplink, the UE can in addition be configured with up to four BWP in the supplementary uplink with a single supplementary uplink BWP being active at a given time. The UE shall not transmit via the Physical Uplink Shared Channel (PUSCH, which is used to transfer RRC signaling messages, application data and Uplink Control Information (UCI)), the Physical Uplink Control Channel (PUCCH, which is used to transfer UCI), or the Sounding Reference Signal (SRS, which is used by the gNB to estimate channel quality) outside of an active BWP.
Unfortunately, the various standards documents do not address uplink scheduling/management issues associated with multiple BWP UE configurations.